Emerg Infect DiseidEmerging Infectious Diseases1080-60401080-6059Centers for Disease Control92042992627603Research ArticlePertussis in The Netherlands: an outbreak despite high levels of immunization with whole-cell vaccine.de MelkerH. E.Conyn-van SpaendonckM. A.RümkeH. C.van WijngaardenJ. K.MooiF. R.SchellekensJ. F.National Institute of Public Health and the Environment, Bilthoven, The Netherlands.Apr-Jun199732175178

In 1996, a sudden increase in pertussis incidence was reported in the Netherlands (2.1 per 100,000 in 1995, 18 per 100,000 in 1996). Although not all potential surveillance artifacts could be excluded, it is highly probable that the data reflect a true outbreak. However, the cause of this increase has not yet been determined. Further research is directed to the severity of disease and a possible mismatch between the vaccine and the circulating Bordetella strains.